Airspace And Airport Types

In September of 1993, the FAA adopted the International Civil Aviation Organization
(ICAO) definition of airspace segments. The ICAO classifications of airspace
are named A through G. The classification of “F” is not used in the USA.

NOTE: It will be helpful while studying this section to have a Sectional
Aeronautical Chart available. Refer to the front panel of the chart as well
as to content of the chart as you study this chapter.

The 3 predominant types of airspace are:

Positive Control (Class A) - White

Controlled (Class E - Yellow )

Uncontrolled (class G) - Magenta

Class G Airspace

ATC exercises no jurisdiction over Class G airspace. It is the airspace
shown in magenta at left, and generally extends from the ground up to 1200
feet above ground level (AGL). As such it is classified as Uncontrolledairspace.

ATC exercises some jurisdiction, at varying degrees to all other airspace.
Thus all other airspace is classifies as Controlled airspace.

Class A - Positive Control

ATC exercises complete control in the Positive Controlled airspace. Jets
are the primary user of Class A airspace. It ranges from 18,000 feet (Flight
Level 180) to 60,000 feet (FL600). Altitudes 18,000 feet and above are called
Flight Levels (FL).

Class A airspace is not specifically charted on aeronautical charts. Operation
is in accordance to Instrument Flight Rules (IFR). The aircraft must be
equipped with appropriate IFR instrumentation, including a Mode C altitude
reporting transponder. The pilot must be instrument rated. An IFR flight
plan is required. ATC exercises full control of route, speed, and altitude.
ATC is responsible for aircraft separation in Class A airspace.

Class E - Controlled

Class E airspace is from altitude 1200 feet Above Ground Level (AGL) up
to 18,000 feet. All airspace from 14,500 feet (MSL) to 18,000 feet (MSL)
is Class E. It contains the Low Altitude Victor airway system. These airways
are designated on the aeronautical charts as blue lines about 1/16 inch
wide, and have numbers like V12, V245, etc. written on them. They are roads
in the sky. All Victor airways are Class E extending 6 nautical
miles each side of the airway centerline. In mountainous terrain, class
G airspace may exist from the surface to 14,500 feet outside the boundaries
of the airway. In non-mountainous terrain (such as Eastern US), all the
airspace above 1200 AGL is Class E unless specified otherwise.

ATC exercises no control over flights operating under Visual Flight Rules
(VFR) in Class E airspace. Radio communication and transponder are not required.
Specific cloud clearance and visibility requirements apply to Class E airspace.
These are listed in the chart at the end of this section. ATC does exercise
control of aircraft operating under Instrument Flight Rules (IFR). IFR flights
must maintain altitudes, routes and speeds a directed by ATC. IFR flights
must be capable of communicating with ATC, and must be Mode C Transponder
equipped (capable of reporting altitude to the radar scope).

There are no specific certification requirements, other than normal pilot
certificates. Class E airspace may be designated from the surface upward
as extension to class B, C, and D airspace (defined later) to accommodate
IFR traffic requirements. Class E airspace will extend downward to 700 feet
AGL around uncontrolled airports that have published instrument approach
procedures.

These areas around uncontrolled airports where the Class E airspace goes
down to 700 feet AGL instead of the standard 1200 feet AGL are depicted
on aeronautical charts by a wide shaded magenta colored band around the
airport. The reason the Class E airspace extends nearer to the ground is
to provide a controlled airspace transition area for aircraft operating
IFR and making an IFR approach.

Class G - Uncontrolled

Most Class G airspace is that space from the surface up to 1200 feet. However,
there are areas in mountainous terrain where airspace outside the Victor
Airways is Class G from the ground to 14,500 feet AGL. Class G space may
underlie Classes B, C, and D, but has no specific symbol indicated on the
chart. The presence of the airspace is implied. Less stringent minimum cloud
clearance and visibility requirements apply to VFR flight in Class G space
since ATC does not maintain jurisdiction over this airspace. See last page
of this section.

As mentioned in the Class E section, airports with published instrument
approached have class E airspace extending down to 700 feet AGL. Obviously,
in these areas, Class G only extends from the surface to 700 feet AGL.

Uncontrolled Airports

Airports without a control tower are classifies as uncontrolled.
Three types of uncontrolled airports are shown below.

The airport on the right does not have an instrument approach or a control
zone around the airport. The airspace overlying this type airport is Class
G up to 1200 feet, then Class E above. It is depicted on the charts as a
magenta circle (unpaved) or a solid circle with white runways (paved).

The airport in the middle has a Class E Control Zone around it, depicted
by the dotted circle around it. If the line is magenta in color, it is a
control zone at an airport where an FAA Flight Service Station (FSS) is
on the field but no control tower. The FSS provides airport traffic advisory
service. Class E airspace extends down to the surface. The zone is depicted
on charts as a dashed MAGENTA circle around the airport. These airports
usually have instrument approach procedures as well.

The airport at left has an instrument approach procedure for the airport.
Such airports have a broad lightly shaded magenta band around them. Within
the outer edge of the band, Class G airspace only extends up to 700 feet
AGL. Class E extends down to 700 feet to provide a transition zone
for aircraft making instrument approaches to the airport. The transition
area is approximately 5 miles in radius.

Controlled Airports

These are airports that have sufficient air traffic to warrant a Control
Tower, and in some cases Approach Control and Ground Control Radar. They
are used by air carrier operations, and can have a mix of jet, high performance
piston and turbine aircraft, as well as smaller single engine aircraft.
The control tower is responsible for aircraft separation within its jurisdiction.
Certain clearances must be obtained from ATC for operations on the airport
surface, and within the controlled airspace around the airport.

There are 3 Classes of airspace around controlled airports. The type of
airspace depends upon the traffic volume and types of flight. These Classes
are B, C, and D airspace

Class D - Airports with Control Tower

The lowest level of control is at airports with a low volume of traffic.
It has a control tower and is depicted on the aeronautical charts as shown
below.

Class D airports are depicted on aeronautical charts by a blue dashed circle
around the airport symbol. Within the dashed circle is a number enclosed
in a dashed square. This number indicates the top of the Class D airspace,
expressed in hundreds of feet (MSL). In the diagram, the top is 4,600 feet
MSL This airspace may have a Class E extension as shown in the diagram for
an IFR approach transition area.

The control tower has jurisdiction within the Class D airspace which is
5 Statute Miles radius around the control tower. The top of the Class D
airspace extends 2500 feet above the surface of the airport. Two way radio
contact must be maintained with the Control Tower while in this airspace.
The pilot should contact the control tower prior to entering
the airspace.

Terminal Radar Service Areas (TRSA)

Some Class D airports have a local radar service called a Terminal Radar
Service Area (TRSA). The service is available for conflict resolution and
traffic sequencing to departing and arriving aircraft. However contact with
the radar is not mandatory and the pilot may decline the service.

These airports are depicted on the aeronautical charts in the normal Class
D manner, but have a dark gray circular line around the airport out at the
boundary of the radar service range. Wilmington NC and Augusta Ga. are examples
of airports with TRSA. There is no specified regulatory radius for the radar
service.

Class C Airspace (Mandatory Radar)

Class C airspace has two concentric tiers. The inner circle is 5 nautical
mile core area extending to 4000 feet above the surface. It is similar in
function to Class D airspace where the tower usually maintains jurisdiction.

A shelf area with an outer radius of 10 nautical miles surrounds the core
area. It extends from 1200 feet AGL to 4000 feet AGL. The airspace is depicted
on charts as 2 concentric magenta circles.

For example, an airport with a surface altitude of 500 feet MSL is depicted
above. The left diagram is a side profile of the airspace. The right diagram
shows how the airspace is depicted on the aeronautical chart.

The ceiling of the Class C airspace is 4,500 feet (MSL). This is calculated
as runway altitude of 500 feet plus 4000 feet. The floor of the outer shelf
is 1,700 feet MSL. (1200 + 500 feet). The space under the shelf is Class
G. These altitudes are indicated by 45 over SFC for the core circle, and
45 over 17 on the outer shelf.

Contact with Approach and Departure Radar Control is mandatory
within the core and shelf airspace. During takeoff and landing, the tower
and radar controller coordinate their activity. You will be told by either
controller when to switch frequency to the other controller. Aircraft must
be capable of two-way communication with the radar facility and the tower.
A 4096 Altitude Reporting (Mode C) Transponder is required when operating
within, under or above Class C airspace.

Before entering Class C airspace, the pilot MUST establish communication
with the radar service. Radio contact with radar and/or tower must be maintained
when in this airspace.

You may request Flight Following Radar Serviceoutside the
10 mile shelf. It may be granted on a workload permitting basis.
The service can usually be provided to about a 20 NM radius of the airport.

Class B - Large Terminal Airports

Large terminal areas such as the New York, Chicago, and Los Angeles areas
have a high volume of air traffic. The airspace around these airports is
under rigid control of ATC, and are called Class B airspace.

AIRCRAFT MUST HAVE ATC CLEARANCE PRIOR TO ENTRY INTO
THIS AIRSPACE.

The airspace is composed generally of three concentric tiers. A core area
around the airport is generally is surrounded by two additional shelf areas
extending approximately 30 nautical mile radius from the primary airport.

The core area extends from the surface to 10,000 feet AGL. The second shelf
has a wider radius and has both a floor and a ceiling. The ceiling is the
same as the inner circle. The floor may vary at differing altitudes in various
sections to accommodate smaller airports that underlie the middle tier of
airspace.

The third shelf extends out approximately 30 nm from the airport. It has
the same ceiling as the other two tiers, but has a higher floor than the
middle shelf. This floor may also be variable in altitude to accommodate
airports lying beneath the Class B airspace.

The actual configuration of the airspace varies to accommodate local operational
requirements. The purpose of the Class B structure is to allow large high
performance jet traffic to transition down to landing at the airport under
IFR procedures, and with positive control and traffic separation.

Mode C Veil

Around Class B airspace is an area called the Mode C Veil.
It is shown as a thin blue concentric line of 30 Nautical Mile radius around
the Class B airport. An altitude reporting Transponder (Mode C) is required
within this area and when operating under the floor or above
the ceiling of the Class B airspace. Radio communication with ATC is not
required as long as you stay outside the Class B airspace.

Special Use Airspace

A number of “special use” airspace areas exist for various usage. It means
that certain activities have been confined to those areas of airspace. Limitations
are placed on aircraft operations in these areas which are not a part of
the activity. These are:

Prohibited areas

Restricted areas

Warning Areas

Military Operations Areas

Alert Areas

Controlled Firing Areas

Military Training Routes

Air Defense Identification Zone

Temporary Restricted Areas

Prohibited and Restricted airspace are regulatory use airspace whose rules
are defined by FAR Part 73. Warning areas, MOA’s, Alert Areas, National
Security Areas, and controlled firing areas are non-regulatory special use
airspace.

Prohibited Areas

These are areas over which flight by civilian aircraft is prohibited by
FAA Regulation. Operation within such an area can be justification for military
interception or other action. The area around the White House in Washington
DC is an example. The symbol is a blue feathered box shown at right with
the words Prohibited in or near the box.

Restricted Areas

These are designated areas in which flight, although not totally prohibited,
are subject to certain restrictions. These areas denote the existence of
unusual, often invisible, hazards to aircraft. Such activities may be artillery
firing, aerial gunnery, or guided missiles. Penetration of these areas without
authorization of the controlling agency may be extremely dangerous. They
are marked on the charts by blue feathered boundaries.

An identifying number such as R-5306 will be listed near or within the area.
A listing on the bottom of the aeronautical chart identifies the area by
number, and indicates the location of the area, the altitude limits of the
space, the time of use, and the name of the controlling agency. It is good
practice to plan to avoid such areas. If penetration of such an area is
planned, the controlling agency should be consulted as to the status of
activity in the area prior to any penetration.

Warning Areas

These are areas outside the 3 mile limit from shore in international airspace.
They are similar to Restricted Areas. Activities which are unusual or may
be dangerous to aircraft may be in progress. They cannot however be designated
as Restricted Areas since they are over international waters

Warning areas are also identified by a blue feathered box with a number
(such as W-74). Information concerning these areas is listed on the aeronautical
charts in the same section as Restricted Areas. One should treat a Warning
Area the same as a Restricted area, and follow the same procedures.

Military Operation Areas (MOA)

MOA's consist of airspace of defined vertical and lateral limits for the
purpose of separating certain military training activities and IFR traffic.
They are depicted by magenta colored feathered areas similarly to Prohibited,
Restricted and Warning areas. They are denoted by names such as Beaufort
MOA within or near the MOA-defined area. ATC can grant clearance to IFR
traffic through an MOA if adequate IFR separation can be assured. If not,
ATC will restrict routing IFR traffic through the area.

Most military training activities necessitate acrobatic or abrupt maneuvers.
Pilots operating under VFR should exercise extreme caution whole flying
in an MOA when military activity is being conducted. Military pilots on
officially designated operations are exempt from conducting aerobatic maneuvers
on the regions of Victor Airways.

VFR pilots should maintain caution when flying through an MOA when it is
active. Pilots should contact a Flight Service Station (FSS) within 100
miles of the MOA to obtain real-time report of activity within the MOA.
Prior to entry, pilots should contact the controlling agency for traffic
advisories. Information about MOAs is listed in the same location on the
aeronautical chart as the Restricted and Warning area information. The data
is printed in Magenta.

Alert Areas

Alert areas are shown on charts to inform pilots of areas where intensive
pilot training or other types of unusual aerial activity may take place.
The area is depicted in a similar manner to the other special use areas,
but indicated by a blue outline with the area crosshatched as shown.

Controlled Firing Areas

These areas contain operations such as artillery firing. They are not marked
on charts, and pilots need not avoid. Spotter aircraft, radar or ground
personnel monitor for aircraft in the area, and firing is suspended immediately
upon the approach of aircraft.

Military Training Routes

Military training routes are used by high speed military aircraft conducting
low and medium level high speed training activity. The routes above 1500
feet AGL are designed to be flown mostly under IFR rules. They may occur
in either IFR or VFR meteorological conditions. The routes at 1500 feet
and below are generally developed to be flown under VFR rules. Flight visibility
must be 5 miles or more, with ceilings 3000 feet or more.

MTR’s with no segment above 1500 feet will be designated by a 4 digit number;
i.e. IR 1206, VR 1207. Routes that include one or more segments above 1500
feet are designated by 3 digit numbers; i.e. IR206, VR207.

The routes are shown on aeronautical charts are gray in color, and will
have numbers like IR718 or VR4003. Vigilance should be observed when operating
near or crossing an MTR. Contact FSS within 100 miles to obtain current
information on the activity along the MTRs. Give FSS your altitude and route
of flight and destination when requesting MTR information.

Temporary Restricted Areas

The FAA may publish temporary restricted areas that may be due natural disaster,
or other events, in which unauthorized civilian flight is inadvisable or
may interfere with rescue or relief efforts. These temporary restrictions
are published through the system called “Notices To Airmen” (NOTAMS). They
are disseminated through the FAA Flight Service Stations. Contact FSS prior
to any flight which may be in the vicinity of such events as air crashes,
earthquake damage, floods, etc.

Airspace Rules

The various types of airspace have rules concerning weather limitations
and equipment requirements for operation in the given airspace. The listing
below summarizes these requirements.

Standard VFR Cloud Clearance and Visibility

Hereinafter, reference will be made to standard VFR Rules for Cloud Clearance
and Visibility. These are: